New type of radial engine.

[Moontanman]

This engine with three spark plugs and five cylinders may end up in certain types of machines that need small efficient powerful engines.

 

http://www.gizmag.com/duke-engines-axial/33631/

[EdEarl]

Seems like containing the compression between the cylinder barrel and spark plug plate would be difficult to seal and prone to wear. I'd like to see one of these in an Indy racer and other endurance races to see how well they survive punishment.

[Carrock]

My first thought .... Seems like a Wankel engine to me.

 

In http://www.gizmag.com/duke-engines-axial/33631/

Seems like a overcomplicated Wankel engine to me.

[Enthalpy]

Not a Wankel. This one has cylindrical pistons that move like usually.

 

The cylinder arrangement is like on an axial hydraulic pump or engine. The "crankshaft" differs a bit from the usual pump construction. The rotating cylinders that move against the immobile head with air inlet and outlet is one possible design for an axial hydraulic pump.

 

One such engine, but with the "crankshaft" resembling more today's hydraulic pumps, was built in the early days of the Diesel engine.

 

I suppose, with no excellent reason, that the standard crankshaft is more efficient. Airtightness, yes... That's solved at hydraulic pumps, but air leaks worse than oil. A race car serviced after 1000km is easier than a consumer car. As well, valves are presently steered for variable inlet and outlet, which the head here may not enable as finely.

[Delbert]

Think I recall something similar some years ago. It consisted of a fairly large number of relatively small pistons arranged radially and operated by cams. The large number of small pistons was presumably to increase volumetric efficiency. But not having ever seen it again, perhaps the cam friction was a problem. Presumably the cam arrangement was to eliminate the need for umpteen crank journals and connecting rods.

 

As for the above, it seems there'll be significant friction between the angled surface and the reciprocator.

[Enthalpy]

Their reciprocator design looks interesting and may be the innovating part in the design. The designers were probably aware of the friction drawback and searched an answer. Could this be transferred to hydraulic pumps and engines?

 

An other drawback I see for the rotating cylinders is the inertia. Much worse that if moving only pistons and a crankshaft. That must be a handicap on a race car, to be compounded with the advantages.

 

On a standard petrol engine with reciprocating pistons and crankshaft, many small cylinders fill and empty more quickly, so they can improve this efficiency or run faster, which gives more power from the same volume and mass. That's why Formula 1 engines had V12 engines in the past, and aeroplanes far more. On big maritime engines it also keeps manageable part size. On consumer cars, the same parts make engines of varied power by changing the number of cylinders.

 

Cams instead of a crankshaft:

- Had they springs to pull the cylinders? Fine on hydraulic machines, serious drawback for combustion engines. At 6,000rpm one has to pull the pistons strongly.

- Friction, sure. Which mean not only losses: it demands better cooling and reduces the parts' life.